Typically, the tracking error comes from two parts: object detection and temporal association. To measure the performance of trackers, three main evaluation metrics, i.e., multi-object tracking accuracy (MOTA) [1]}, IDF1 score [2]} and higher order tracking accuracy (HOTA) [3]}, are widely used in MOT field. As demonstrated in [3]}, MOTA emphasizes detection accuracy while IDF1 focuses more on association measurement. As shown in Figure REF , generally, the association errors can be concluded into two categories: 1) different objects are associated to the same tracklet, 2) tracklets from the same object are assigned to different IDs. A good tracker should reduce these two types of errors as much as possible in the association task. Due to missing detection, change of lighting condition, camera movement, occlusion and object deformation, the association is one of the major challenges of almost all existing trackers.
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